Apparatus and method for reducing the residual bending and fatigue in coiled tubing

ABSTRACT

The subject disclosure provides a reel and a gooseneck which significantly reduce residual bending of the coiled tubing. The subject disclosure discloses a gooseneck that provides reverse bending forces to reduce the residual bending as a result of the reel. Further, the subject disclosure discloses a gooseneck having an adjustable radius during the coiled tubing operations which optimizes the residual bending process. The subject disclosure also discloses a heating and cooling module. The heating and cooling modules are attached to the gooseneck and are used to reduce fatigue of the coiled tubing and elongate the life cycle of the coiled tubing.

FIELD OF THE DISCLOSURE

The subject disclosure generally relates to the field of coiled tubingand coiled tubing applications in hydrocarbon wells. More particularly,the subject disclosure relates to reducing residual bending and fatigueof coiled tubing.

BACKGROUND OF THE DISCLOSURE

Coiled tubing refers to metal piping, used for interventions in oil andgas wells and sometimes as production tubing in depleted gas wells,which comes spooled on a large reel. Coiled tubing operations typicallyinvolve at least three primary components. The coiled tubing itself isdisposed on a reel and must, therefore, be dispensed onto and off of thereel during an operation. The tubing extends from the reel to aninjector. The injector moves the tubing into and out of the wellbore.Between the injector and the reel is a tubing guide or gooseneck. Thegooseneck is typically attached or affixed to the injector and guidesand supports the coiled tubing from the reel into the injector.Typically, the tubing guide is attached to the injector at the pointwhere the tubing enters. As the tubing wraps and unwraps on the reel, itmoves from one side of the reel to the other (side to side).

Residual bend exists in every coiled tubing string. During storage andtransportation, a coiled-tubing string is plastically deformed (bent) asit is spooled on a reel. During operations, the tubing is unspooled(bent) from the reel and bent on the gooseneck before entering into theinjector and the wellbore. Residual bending is one of the technicalchallenges for coiled tubing operations and originates from the spool ofthe coiled tubing on the reel. Although the reel is manufactured in adiameter as large as possible to decrease the residual bending incurredon the coiled tubing, the maximum diameter of many reels is limited toseveral meters due to storage and transportation restrictions.

Coiled tubing is susceptible to a condition known as helical buckling ofthe tubing which leads to lockup. Residual bending of the coiled tubingincrease the susceptibility of the coiled tubing to helical buckling andlockup. As the coiled tubing goes through the injector head, it passesthrough a straightener; but the tubing retains some residual bendingstrain corresponding to the radius of the spool. That strain gives thetubing a helical form when deployed in a wellbore and can cause it towind axially along the wall of the wellbore like a long, stretchedspring. Ultimately, when a long enough length of coiled tubing isdeployed in the well bore, frictional forces from the wellbore wallrubbing on the coiled tubing cause the tubing to bind and lock up,thereby stopping its progression. Lock up limits any further progressionas the coiled tubing cannot be pushed further by a force applied at thesurface. (Lubinski, A., Althouse, W. S., and Logan, J. L., “HelicalBuckling of Tubing Sealed in Packers,” SPE 178, 1962). Such lock uplimits the use of coiled tubing as a conveyance member for logging toolsin highly deviated, horizontal, or up-hill sections of wellbores.Therefore, reducing the residual bending of the coiled tubing before thecoiled tubing is placed into the wellbore can increase the extendedreach of the coiled tubing (Zheng, A. and Adnan, S., “The Penetration ofCoiled Tubing with Residual Bend in Extended-Reach Wells,” SPE 95239,2007). Residual bending also decreases the fatigue life for coiledtubing, therefore, reducing residual bending will thus increase thefatigue life of coiled tubing (Bhalla, K., “Coiled Tubing Extended ReachTechnology,” SPE 30404, 1995). Fatigue failure of coiled tubing is aserious concern because of plastic deformation caused by repeatedbending on the reel and gooseneck.

Coiled tubing passing downward (generally running-in hole) undergoes atleast three straining events: 1) as the coiled tubing is straightenedupon leaving the reel and on approach to the gooseneck; 2) as the coiledtubing is curved over the gooseneck; and 3) as the coiled tubing isstraightened on its way from the gooseneck to the injector head.Similarly, coiled tubing passing upward (generally pulling-out-of-hole)undergoes at least three straining events: 1) as the coiled tubing isextracted from the wellbore and curved over the gooseneck; 2) as thecoiled tubing is straightened upon leaving the gooseneck and on approachto the reel; and 3) as the coiled tubing is being curved onto the reel.These strains in coiled tubing may cause residual bend in the tubingwhich may prevent it from straightening properly in the borehole orrolling properly on the reel.

Residual bending is reduced by the straightener. The straightenerapplies compressive forces around the coiled tubing before the coiledtubing is placed into the wellbore, straightening the coiled tubing andreducing some of the residual bending in the coiled tubing. However, thetubing retains some residual bending. Furthermore, the straightener isunable to reduce fatigue of the coiled tubing or elongate the life cycleof the coiled tubing.

Mueller et al, (U.S. Pat. No. 5,291,956) proposes a method for reducingthe residual bending using a pulley. However, the pulley has a diameternear to the diameter of the reel and occupies additional space for thecoiled tubing unit.

The presently disclosed subject matter addresses the problems of theprior art by addressing residual bending and fatigue of the coiledtubing. The presently disclosed subject matter reduces residual bendingand fatigue of the coiled tubing, which assists in extending the maximumreach of the coiled tubing in the wellbore and the life cycle of thecoiled tubing respectively.

SUMMARY OF THE DISCLOSURE

In view of the above there is a need for an improved mechanism whichreduces residual bending in coiled tubing. Further there is a need foran improved mechanism to reduce fatigue of the coiled tubing andelongate the life cycle. The subject technology accomplishes these andother objectives. The subject disclosure provides a method of reducingresidual bending and fatigue in the coiled tubing by utilizing a reeland gooseneck. The subject disclosure discloses a gooseneck thatprovides an opposite bending moment to reduce the residual bending inthe coiled tubing as a result of the reel. Further, the subjectdisclosure discloses a gooseneck having an adjustable radius during thecoiled tubing operations which optimizes the residual bending reductionprocess. The subject disclosure also discloses a heating and coolingmodule. The heating and cooling modules are attached to the gooseneckand are utilized to increase the efficiency of the residual bendingprocess and reduce fatigue of the coiled tubing.

In accordance with an embodiment of the subject disclosure, an apparatusfor reducing residual bending in coiled tubing is disclosed. A gooseneckis positioned to receive the coiled tubing from the coiled tubing reeland once positioned reverse bends the coiled tubing to an extentsufficient to remove residual bend resulting from the coiled tubingbeing coiled on the reel.

In accordance with a further embodiment of the subject disclosure, amethod for reducing residual bend from a reel is disclosed. A gooseneckis positioned to reverse bend the coiled tubing sufficiently to removeresidual bend resulting from the coiled tubing being coiled on the reel.

Further features and advantages of the subject disclosure will becomemore readily apparent from the following detailed description when takenin conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows the coiled tubing operating environment for the subjectdisclosure;

FIG. 2 represents a coiled tubing unit having a hydraulically operatedtubing reel and shows the bending events that coiled tubing undergoeswhile moving from the coiled tubing reel to the main injector;

FIG. 3 illustrates one embodiment of the subject disclosure;

FIG. 4 illustrates a second embodiment of the subject disclosure;

FIG. 5 illustrates the embodiment of FIG. 1 with a heating and coolingmodule;

FIG. 6 illustrates the embodiment of FIG. 2 with a heating and coolingapparatus;

FIG. 7 illustrates a gooseneck having an adjustable radius of curvature;and

FIG. 8 is the bending moment M—curvature 1/ρ curve of coiled tubingunder elastically-perfectly plastic deformation.

DETAILED DESCRIPTION

Embodiments of the present technology comprise a reel and a gooseneckwhich significantly reduce residual bending of the coiled tubing.

In FIG. 1 the operating environment of the subject disclosure is shown.Coiled tubing operation comprises a truck 103 and/or trailer 109 thatsupports power supply 105 and tubing reel 107. An injector unit head 111feeds and directs coiled tubing 113 from the tubing reel into thesubterranean formation. The configuration of FIG. 1 shows a horizontalwellbore configuration which supports a coiled tubing trajectory 115into a horizontal wellbore 117. The subject disclosure is not limited toa horizontal wellbore configuration but may also be used in vertical anddeviated wells, both on land and offshore. Downhole tool 119 isconnected to the coiled tubing, as for example, to conduct flow ormeasurements, or perhaps to provide diverting fluids.

FIG. 2 depicts a coiled tubing assembly 211. The coiled tubing assembly211 is composed of coiled tubing 203, reel 201 and a gooseneck 205. Whenthe coiled tubing assembly is run into the wellbore the coiled tubing203 spooled onto the reel 201 is unwound first and then deliveredthrough a levelwind assembly 212 and a coiled tubing brake 214 in acontrollable way. The coiled tubing spooled on the reel 201 isplastically deformed, resulting in residual bending in the coiledtubing. The forces and strains placed upon coiled tubing when it is usedin a coiled tubing unit 211 are apparent from viewing FIG. 2. Coiledtubing undergoes numerous bending events each time it is run into andout of a wellbore. Coiled tubing 203 is straightened when it emergesfrom the reel by way of the levelwind assembly 212. A levelwind assemblyfor a coiled tubing reel guides coiled tubing onto a reel when thecoiled tubing is removed from an oil or gas well and guides coiledtubing from the reel when the coiled tubing is injected into an oil orgas well. Levelwind assemblies are known to those skilled in the art.One such levelwind assembly is describe in U.S. Pat. No. 6,264,128,entitled “Levelwind Assembly for Coiled Tubing Reel”, incorporatedherein in its entirety by reference. Coiled tubing brake 214 on thelevelwind assembly 212 is shown. The coiled tubing 203 is guided by thegooseneck 205, and is straightened as it goes into the injector head 207for entry into the wellbore. Of course, each bending event is repeatedin reverse when the tubing is later extracted from the wellbore. Thesebending events weaken the tubing each time it is used, and tubing usemust be monitored. Tubing is discarded when it has been used beyond anacceptable safety limit as indicated by reaching predicted fatiguelimits. The coiled tubing, typically made of steel, is plasticallydeformed every time it is spooled off the reel, bent over the gooseneck,straightened through the chains, and in the reverse process. It is knownthat the fatigue resistance of steel is severely degraded when it isplastically deformed. Residual bending in the coiled tubing 203 is notreduced when the coiled tubing 203 is guided by the gooseneck 205. Whenthe coiled tubing 203 slides through the injector head 207, the injectorhead 207 exerts a compressive force around the coiled tubing whichstraightens the coiled tubing. Finally, after the coiled tubing isstraightened by the injector head 207, the residual bending in thecoiled tubing 209 is reduced before the coiled tubing 209 is run intothe wellbore.

FIG. 3 show a reel 301 of coiled tubing 305 stored on a drum in aclockwise direction 309. As the coiled tubing 305 slides through thegooseneck 303 the coiled tubing 305 unwinds in a counter-clockwisedirection 311, and continues unwinding in a counter-clockwise direction311 as it is placed into a wellbore (not shown). The reel 301 spooledwith coiled tubing 305 rotates in a clockwise direction 309 while thecoiled tubing 305 is guided by the gooseneck 303 in a counter-clockwisedirection 311 when the coiled tubing is run into a wellbore. Once thecoiled tubing 305 leaves the reel 301, the residual bending existing inthe coiled tubing 305 is compensated by an opposite bending momentexerted by the gooseneck 303 and the residual bending in the coiledtubing 307 is reduced. The opposite bending moment means the sign of thebending moment M is different, i.e. clockwise or anti-clockwise. Oncethe coiled tubing 305 has travelled through the gooseneck 303, residualbending in the coiled tubing 305 will be significantly reduced. Residualbending of the coiled tubing is significantly reduced as a result of thereverse unwinding of the coiled tubing, in this instance in acounter-clockwise direction. The radius profile of the gooseneck 303 isadjustable during the coiled tubing operation for optimal reduction ofresidual bending.

FIG. 4 shows a reel 401 of coiled tubing 403 stored on a drum in acounter-clockwise direction 411. The reel 401 spooled with coiled tubing403 rotates in a counter-clockwise direction 411 and the coiled tubingis guided by a first section of the gooseneck 409 in the samecounter-clockwise direction when running the coiled tubing into well. Asecond section of the gooseneck 407 enables rotation of the coiledtubing in a clockwise direction 415. The coiled tubing 403 enters afirst section 409 of the gooseneck in a counter-clockwise direction 413.The gooseneck further comprises a second section 407. The coiled tubing403 enters in a clockwise direction 415 into the second section 407 ofthe gooseneck. The residual bending existing in the coiled tubing 403 iscompensated by an opposite bending moment exerted by the second section407 of the gooseneck on the coiled tubing 403 and the residual bendingin the coiled tubing 405 is reduced. Once the coiled tubing movesthrough the second section 407 of the gooseneck the residual bending inthe coiled tubing 403 will be significantly reduced. The radius profileof the second section 407 of the gooseneck is adjustable for optimalreduction of residual bending.

FIG. 5 illustrates the schematic of FIG. 3 further comprising a heatingand cooling module. FIG. 5 depicts a reel 505 of coiled tubing 507stored on a drum in a clockwise direction 513. A heating module 503 isattached to the gooseneck 501 and a cooling module 509 surrounds thecoiled tubing 507. The heating module 503 heats the coiled tubing 507and enables the residual bending reduction process in a hightemperature. In certain non-limiting examples the temperature may reach600° C. A high temperature increases the efficiency of reducing residualbending and reducing fatigue of the coiled tubing 507. The coolingmodule 509 controls the temperature of the coiled tubing 507 ensuringthe high temperature is in an area close to the gooseneck 501. Thus, thecooling module 509 confines the high temperature of the coiled tubing507 to a region close to the gooseneck 501.

FIG. 6 illustrates the schematic of FIG. 4 further comprising heatingand cooling modules. FIG. 6 depicts a reel 609 of coiled tubing 613stored on a drum in a counter-clockwise direction 615. A heating module603 is attached to a second section 603 of gooseneck and a coolingmodule 605 surrounds the coiled tubing 613 on either end of thegooseneck 601. Similar to the embodiment of FIG. 5 the heating module603 heats the coiled tubing 605 and enables the residual bendingreduction process in a high temperature. A high temperature increasesthe efficiency of reducing residual bending and reducing fatigue of thecoiled tubing 605. The cooling module 605 controls the temperature ofthe coiled tubing 605 ensuring the high temperature is in an area closeto the second section 611 of the gooseneck. Thus, the cooling module 605confines the high temperature of the coiled tubing 613 to a region closeto the area of the second section 611 of the gooseneck.

The configuration of the gooseneck 303 and the second section of thegooseneck 407 are adjustable during an individual coiled tubingoperation or multiple coiled tubing operations. For the individualcoiled tubing operation, the configuration of the gooseneck 303 or 407changes as different locations of the coiled tubing are guided by thegooseneck 303 or 407. The magnitude of the residual bending of thecoiled tubing varies depending on the location of the coiled tubing onthe reel. The coiled tubing spooled on the outside of the reelexperiences less plastic deformation than the coiled tubing spooled onthe inner side of the reel. The radius of curvature of the gooseneck 303or 407 may be adjusted from a large curvature to a smaller curvature asmore coiled tubing is unwound from the reel when the coiled tubing isrun into the wellbore.

For the multiple coiled tubing operations, the configuration of thegooseneck 303 or 407 changes as the diameter of the reel changes. Themagnitude of the residual bending of the coiled tubing varies dependingon the diameter of the reel. The coiled tubing spooled on large reelsexperiences less plastic deformation than the coiled spooled on smallerreels. The radius of curvature of the gooseneck 303 or 407 is adjustedto a larger radius if the coiled tubing is spooled on a larger reel. Theradius of curvature of the gooseneck 303 or 407 is adjusted to a smallerradius if the coiled tubing is spooled on a smaller reel.

FIG. 7 schematically illustrates a gooseneck 701 with an adjustableradius of curvature. The gooseneck has the largest radius of curvaturewhen segment 714, segment 715, segment 716, and the plurality of othersegments (not listed) are expanded. Joint 713 is fixed on the segment714. Joint 705 and joint 709 are fixed on the gooseneck base 703. Whenthe radius of curvature of the gooseneck decreases, segment 715collapses into segment 714. At the same time, upper supporting arms 711rotate around joint 713 and lower supporting arms 707 rotate aroundjoint 705 and joint 709 to achieve a new balanced position. When theradius of curvature of the gooseneck further decreases, segment 716 alsocollapses into segment 714, upper arms 711 and lower arms 707 changetheir positions accordingly, to a different balanced position. Oneskilled in the art will appreciate that adjusting the radius ofcurvature can be accomplished using many other techniques known to thoseskilled in the art and not described in the subject disclosure.

The significance of the residual bending can be described quantitativelyby using bending strain. The maximum magnitude of the bending strainε_(max) in a given pipe cross-section usually occurs on the outside ofthe pipe. The radius of the reel is ρ₀ and the coiled tubing outsidediameter is D_(o). When the number of the loops of the coiled tubingspooled on the reel is n, the curvature ρ of the coiled tubing of thei^(th) loop is:

ρ=β₀ +i·D _(o)(i=1, 2 . . . n)  (1)

The relationship between the maximum bending strain ε_(max), curvature1/ρ, and the pipe outside diameter D_(o) is:

|ε_(max)|=|(D _(o)/2)(1/ρ)|  (2)

As can be seen from Eq. (2), the residual bending is significant whenthe pipe outside diameter D_(o) is large and the radius ρ is small. Ascan be seen from Eq. (1), the radius ρ is small when the radius of thereel ρ_(o) is small and the number of the loops n is small.

FIG. 8 depicts the bending moment M—curvature (ρ) of a pipe undergoing aseries of deformations. In a non-limiting example this pipe may be aportion of coiled tubing. The material is assumed to beelastically-perfectly plastic. In a first deformation from A to B thepipe undergoes linear elastic bending. Further bending from B to Cresults in deformation which is elastic-plastic, this means that someparts of a cross-section are deforming plastically and some parts of across-section are deforming elastically. The deformation from A to C maybe representative of placing a straight coiled tubing string onto areel. The pipe unloads elastically from C-D, the curvature at D would bethe residual bend if no further deformation occurred e.g. if a coiledtubing was unwound from the reel without a straightening process. If thepipe is then straightened, the deformation will unload elastically fromD to E and then elastically-plastically from E to F. At F, the pipe willbe straight. If the pipe then unloads elastically, it will proceed fromF to G and have a residual bend shown by the curvature at G. If the pipeis then reverse-bent, the deformation will proceed from F to G′, withfurther elastic-plastic deformation. Upon unloading elastically from G′,the pipe returns to the initial state A with no residual bend, providingG′ has been selected appropriately. In one non-limiting example G′ wouldbe estimated by reverse bending to the same curvature as seen at G, i.e.reverse bending by the same amount as the residual curvature if in theabsence of the reverse bend operation.

Reverse bending may also occur elsewhere in the coiled tubing e.g.injector. Although the embodiments of the subject disclosure have beendescribed with respect to coiled tubing, the mechanisms disclosed mayreduce residual bending of tubing in general.

While the subject disclosure is described through the above exemplaryembodiments, it will be understood by those of ordinary skill in the artthat modification to and variation of the illustrated embodiments may bemade without departing from the inventive concepts herein disclosed.Moreover, while the preferred embodiments are described in connectionwith various illustrative structures, one skilled in the art willrecognize that the system may be embodied using a variety of specificstructures. Accordingly, the subject disclosure should not be viewed aslimited except by the scope and spirit of the appended claims.

1) An apparatus for reducing residual bending in coiled tubing from areel comprising: a gooseneck positioned to receive the coiled tubingfrom the coiled tubing reel and to cause the coiled tubing to reversebend to an extent sufficient to remove residual bend resulting from thecoiled tubing being coiled on the reel. 2) The apparatus of claim 1wherein the gooseneck guides the coiled tubing in a second rotationdirection opposite to a first rotation direction of the coiled tubing onthe reel. 3) The apparatus of claim 1 wherein a radius of curvature ofthe gooseneck is adjustable. 4) The apparatus of claim 3 wherein amagnitude of the reverse bend is controlled by adjusting the radius ofcurvature of the gooseneck. 5) The apparatus of claim 1 wherein thegooseneck further comprises: a first section of gooseneck guiding thecoiled tubing in a first rotation direction and a second section ofgooseneck guiding the coiled tubing in a second rotation directionopposite to the first rotation direction. 6) The apparatus of claim 5wherein the first rotation direction is the same as a rotation directionof the coiled tubing on a reel. 7) The apparatus of claim 5 wherein aradius of curvature of the second section of gooseneck is adjustable. 8)The apparatus of claim 1 wherein a portion of the gooseneck comprises aplurality of segments. 9) The apparatus of claim 8 wherein the pluralityof segments are used to adjust a radius of curvature. 10) The apparatusof claim 8 wherein the plurality of segments are collapsible thusdecreasing a radius of curvature. 11) The apparatus of claim 8 whereinthe plurality of segments are expandable thus increasing a radius ofcurvature. 12) The apparatus of claim 4 wherein the radius of curvaturechanges as a diameter of the reel changes. 13) The apparatus of claim 4wherein the radius of curvature changes as the coiled tubing is wound orunwound from the reel. 14) The apparatus of claim 1 further comprising aheating module and a cooling module. 15) The apparatus of claim 14wherein the heating module is attached to the gooseneck. 16) Theapparatus of claim 14 wherein the cooling module is wrapped around thecoiled tubing proximal to the gooseneck. 17) The apparatus of claim 16wherein the cooling module confines a high temperature of the coiledtubing to an area proximal to the gooseneck. 18) A method for reducingresidual bending in coiled tubing from a reel comprising: positioning agooseneck and receiving the coiled tubing from the coiled tubing reelwith the positioned gooseneck; with the positioned gooseneck causing thecoiled tubing to reverse bend to an extent sufficient to remove residualbend resulting from the coiled tubing being coiled on the reel. 19) Themethod of claim 18 wherein with the gooseneck guiding the coiled tubingin a second rotation direction opposite to a first rotation direction ofthe coiled tubing on a reel. 20) The method of claim 18 wherein thegooseneck further comprises: a first section of gooseneck guiding thecoiled tubing in a first rotation direction and a second section ofgooseneck guiding the coiled tubing in a second rotation directionopposite to the first rotation direction. 21) The method of claim 20wherein the first rotation direction is the same as a rotation directionof the coiled tubing on a reel. 22) The method of claim 18 furthercomprising: adjusting a radius of curvature of the gooseneck.